A solar clock that isn’t a sundial

Hack a Day’s very own [Jack Buffington] is throwing his hat into the ring for the Buildlounge laser cutter giveaway with his solar clock that isn’t a sundial.

The theory behind [Jack]’s clock is pretty simple. The light from the sun will be captured by a camera obscura/pinhole camera. The sun’s rays shine on dozens of optical fibers that lead indoors and up to the clock. These glass fibers go to pinholes in the face of the clock which light up, showing the time.

[Jack] already cut out the face of the clock on his (awesome) home-made CNC router. He hasn’t gotten around to cutting out the mechanics of the clock face so the clock can be adjusted throughout the year. We’re okay with that, because we’re really not ready to see [Jack] fiddle with his gnomon. At least before [Jack] gets his hand on the Buildlounge laser.

The next major hurdle of the build is the solar collector that collects light into different optical fibers. That’s going to involve a lot of math using the equatorial coordinate system. Help is available, though.

Check out [Jack] cutting the clock face on his router after the break.

Well, just read here: http://blog.robotbrigade.com/?p=41
The clock’s face shown in the photo has nothing to do with collecting or reflecting sun rays. It’s rather like this:

1) sunbeams enter a box through a small pinhole that makes it actually a camera obscura. The shape of the sun moves along a path inside the box. As the camera obscura flips the image like a lens, the “hot spot” inside the box is far left if the sun shines from far right
2) on the backside wall of the box where the sunbeams arrive, they are picked up by glass fibers along this path the sun walks through over the day
3) Say, far right is equal to 6:00 in the morning, then the fibers from far right on the box backside wall go to the 6-hours pinhole in the clock face
4) this illuminates only the 6-hours pinhole in the clock face, not any of the others – well, some of the sunlight may spread to the neighbor 5-hours and 7-hours fibers because eventually that depends on the clearness of the sun’s shape – if it is hazy outside, the sun won’t create an exact spot in the camera obscura but rather a blurry circle

It’s a cool idea. As glass fibers can be pretty long without too much loss, the clock face can be considerably far away from the collector box.
Plus, there is still potential for Arduino integration. If there is no sunlight or it is too clouded for the sun to come through, microcontrolled LEDs might kick in as light sources ;o)

And even though it is unfinished, it shows a whole lot of creativity. Not all hacks require a power supply of some sort.

Or the Arduino could collect the position of the spot through a bunch of photoresistors or, better an old webcam, use ephemerides to convert the position of the sun to time depending on the date and serve it as an NTP server using an ethernet or better a Wi-Fi shield?
All this with PoE of course.

Nice idea, hope it works as planned. But I think the light indicating the early morning,and late after noon time will be pretty dim if it works at all, with a single aperture, that I assume will work best a mid day. Maybe multiple apertures to track the sun so the indicator at the correct time is the brightest? I seen where another commenter wants you to use an arduino,just use an arduino to control the position of the aperture. :) Have the clock on the right building during a solar eclipse, you have a means to view the eclipse indoors,far out.